Magnetic tape provides a means for physically storing data. As an archival medium, tape often comprises the only copy of the data. The tape is typically made as thin as practically possible to maximize the length of a tape stored on a tape reel, and thereby maximize the amount of data that can be stored on the tape contained in a single cartridge. A tape drive is used to store and retrieve data with respect to the magnetic tape. An example of a tape drive is the IBM TotalStorage Enterprise Tape Drive 3592 manufactured by IBM Corporation. Tape drives are typically used in combination with an automated data storage library. For example, the IBM TotalStorage Enterprise Tape Library 3494 manufactured by IBM Corporation is an automated data storage library that may include one or more tape drives and data storage media for storing data with respect to the tape drives.
FIG. 1 illustrates an exemplary configuration of a known write mechanism of a tape drive employing a write current driver (“WCD”) circuit 50 having four (4) write current drivers in the form of an H-configuration of electronic switches S1-S4, which are electrically disconnected from a write head 30. Under normal write conditions, opened electronic switches S1 and S4 can be closed as shown in FIG. 2 to electrically connect write current driver circuit 50 to Write head 30 via a drive card 40 and a pair of cables C1 and C2 whereby a write current IW flows from a power supply 60 through write head 30 to a power return 61 in a first direction as indicated by the arrows. Similarly, opened electronic switches S2 and S3 can be closed as shown in FIG. 3 to electrically connect write current driver circuit 50 to write head 30 via drive card 40 and cables C1 and C2 whereby write current IW flows from power supply 60 through write head 30 to power return 61 in a second opposing direction as indicated by the arrows.
Under an open write condition, the write current IW will not flow through write head 30 upon a closing of electronic switches S1 and S4 or a closing of electronic switches S2 and S3. For example, as shown in FIG. 4, an open condition OC1 of write head 30, an open condition OC2 of cable C1 and/or an open condition OC3 of drive card 40 will impede a flow of write current IW from power supply 60 through write head 30 to power return 61. Consequently, the storage industry is constantly striving to improve upon techniques for detecting a presence of an open write condition of a storage drive.